The Effects of Changing the Painful Stimulus upon Dolorimetry Scores in Patients with Fibromyalgia

Objectives: Several previous studies have used the dolorimeter as a measure of disease activity in patents with fibromyalgia. We asked the question: does changing either the dolorimeter to skin surface contact area, or the rate of dolorimeter pressure application effect the subsequently recorded tenderness scores? Methods: Twenty-one women who met the ACR classification criteria for fibromyalgia underwent dolorimetry testing on two separate occasions. First, we compared dolorimetry scores obtained using two different-sized dolorimeter heads [surface areas 2.01 cm and 0.95 cm]. Secondly, we compared scores obtained when changing the rate at which dolorimeter pressure was increased [1 kg per 1 second versus 1 kg per 3 seconds]. Data was analyzed by multiple analysis of variance. Results: Statistically lower dolorimeter scores were obtained when using the smaller-sized dolorimeter head [P <. 05 at 13 of 24 points], and when applying pressure at a slower rate [P <. 05 at 21 of 24 points]. The effect of rate on dolorimetry scores was greater than the effect of dolorimeter size. Conclusions: The technique by which dolorimetry testing is done is clearly important. Dolorimeter surface area and application rate must be accounted for and standardized.